Various types of pressurized devices are used in industry and there are many manual techniques for evaluating pressurization of such devices. For example, gas springs are one type of pressurized device and are typically used to yieldingly resist movement of a body such as a clamping ring for a metal blank in a die of a press for forming sheet metal parts. These springs are generally constructed with a piston slidably received in a cylinder and defining a pressure chamber charged with a gas, such as nitrogen.
To charge the pressure chamber, pressurized gas is introduced into the pressure chamber in the cylinder through a filler valve until the pressure of the gas within the pressure chamber meets or exceeds a predetermined minimum pressure, such as about 200 to 2,000 PSI. This provides a pressurized cushion at a first end of the piston to permit the piston to yieldably move toward its retracted position when a force, applied to another end of the piston, exceeds the force of the pressurized gas acting on the first end of the piston. In typical use, as the piston approaches its retracted position, thereby decreasing the volume of the gas chamber, the pressure within the chamber may increase, for example, to 5,000 psi or more.
In some applications, the gas pressure within the pressure chamber may fall below the predetermined minimum pressure, for example, because of wear or degradation of a sealing method in the gas spring. In some current applications, an operator must stop an operation, clear obstructions around the gas spring or remove the gas spring from the press, and use external devices to evaluate the gas spring for proper minimum pressure. For example, an operator may have to use a pressure gage to tap into a port of the gas spring to sample the pressure therein. In another example, an operator may have to place a load cell between the gas spring and a movable component and infer the gas pressure in the gas spring based on the load cell readings. In other current applications, analog pressure monitoring devices such as Bourdon tubes may be placed in fluid communication with the pressure chamber of the gas spring.